Oxime ester compound and photopolymerization initiator containing the same

ABSTRACT

An oxime ester compound represented by general formula (I): 
                         
wherein R 1  and R 2  each independently represent R 11 , OR 11 , COR 11 , SR 11 , CONR 12 R 13 , or CN; R 11 , R 12 , and R 13  each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, or a heterocyclic group having 2 to 20 carbon atoms, R 3  and R 4  each independently represent R 11 , OR 11 , SR 11 , COR 11 , CONR 12 R 13 , NR 12 COR 11 , OCOR 11 , COOR 11 , SCOR 11 , OCSR 11 , COSR 11 , CSOR 11 , CN, a halogen atom, or a hydroxyl group; a and b each independently represent 0 to 4; X represents an oxygen atom, a sulfur atom, a selenium atom, CR 31 R 32 , CO, NR 33 , or PR 34 ; R 31 , R 32 , R 33 , and R 34  each independently represent R 11 , OR 11 , COR 11 , SR 11 , CONR 12 R 13 , or CN.

TECHNICAL FIELD

This invention relates to a novel oxime ester compound useful as a photopolymerization initiator in a photosensitive composition, a photopolymerization initiator containing the compound as an active ingredient, and a photosensitive composition containing a polymerizable compound having an ethylenically unsaturated bond and the photopolymerization initiator.

BACKGROUND ART

A photosensitive composition contains a polymerizable compound having an ethylenically unsaturated bond and a photopolymerization initiator. A photosensitive composition polymerizes to cure on being irradiated with light of 405 nm or 365 nm and is used in photo-curing inks, photosensitive printing plate precursors, and various photoresists.

Patent documents 1 to 8 listed below propose using an O-acyl oxime compound having a carbazolyl structure as a photopolymerization initiator of a photosensitive composition. However, the known O-acyl oxime compounds are not sufficiently satisfactory particularly in sensitivity.

-   Patent document 1: JP 2001-302871A -   Patent document 2: JP 2004-534797A -   Patent document 3: JP 2005-25169A -   Patent document 4: JP 2005-128483A -   Patent document 5: JP 2005-242279A -   Patent document 6: JP 2005-242280A -   Patent document 7: JP 2006-16545A -   Patent document 8: Japanese Patent 3754065

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

The problem to be solved is that there has been no photopolymerization initiator having satisfactory sensitivity.

Accordingly, an object of the invention is to provide a highly sensitive photopolymerization initiator that efficiently absorbs light of long wavelength, e.g., 405 nm or 365 nm, to be activated.

Means for Solving the Problem

The above object is accomplished by the provision of an oxime ester compound represented by general formula (I) below and a photopolymerization initiator containing the oxime ester compound as an active ingredient.

wherein R¹ and R² each independently represent R¹¹, OR¹¹, COR¹¹, SR¹¹, CONR¹²R¹³, or CN; R¹¹, R¹², and R¹³ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, or a heterocyclic group having 2 to 20 carbon atoms, in which the alkyl group, aryl group, arylalkyl group, and heterocyclic group may have their hydrogen atom substituted with OR²¹, COR²¹, SR²¹, NR²²R²³, CONR²²R²³, —NR²²—OR²³, —NCOR²²—OCOR²³, —C(═N—OR²¹)—R²², —C(═N—OCOR²¹)—R²², CN, a halogen atom, —CR²¹═CR²²R²³, —CO—CR²¹═CR²²R²³, a carboxyl group, or an epoxy group; R²¹, R²², and R²³ each independently represent a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, or a heterocyclic group having 2 to 20 carbon atoms; the methylene units of the alkylene moiety of the substituents represented by R¹¹, R¹², R¹³, R²¹, R²², and R²³ may be interrupted by an unsaturated linkage, an ether linkage, a thioether linkage, an ester linkage, a thioester linkage, an amide linkage, or a urethane linkage at 1 to 5 sites thereof; the alkyl moiety of the substituents represented by R¹¹, R¹², R¹³, R²¹, R²², and R²³ may be branched or cyclic; an alkyl terminal of the substituents represented by R¹¹, R¹², R¹³, R²¹, R²², and R²³ may have an unsaturated bond; R¹² and R¹³, and R²² and R²³ may be connected to each other to form a ring; R³ and R⁴ each independently represent R¹¹, OR¹¹, SR¹¹, COR¹¹, CONR¹²R¹³, NR¹²COR¹¹, OCOR¹¹, COOR¹¹, SCOR¹¹, OCSR¹¹, COSR¹¹, CSOR¹¹, CN, a halogen atom, or a hydroxyl group; a and b each independently represent 0 to 4; X represents an oxygen atom, a sulfur atom, a selenium atom, CR³¹R³², CO, NR³³, or PR³⁴; R³¹, R³², R³³, and R³⁴ each independently represent R¹¹, OR¹¹, COR¹¹, SR¹¹, CONR¹²R¹³, or CN; R³ may be connected to one of the carbon atoms of the benzene rings neighboring via —X— to form a cyclic structure; or R³ and R⁴ may be connected to each other to form a ring; and R³¹, R³³, and R³⁴ may be connected to either one of the neighboring benzene rings to form a ring.

The invention also provides a photosensitive composition containing the photopolymerization initiator and a polymerizable compound having an ethylenically unsaturated bond.

The invention also provides an alkali-developable photosensitive resin composition containing the photopolymerization initiator and an alkali-developable compound having an ethylenically unsaturated bond.

The invention also provides a colored alkali-developable photosensitive resin composition comprising the alkali-developable photosensitive resin composition and a colorant.

BEST MODE FOR CARRYING OUT THE INVENTION

The oxime ester compound of the invention and a photopolymerization initiator containing the compound as an active ingredient will be described in detail.

In general formula (I), examples of the alkyl group as represented by R¹¹, R¹², R¹³, R²¹, R²², R²³, R³¹, R³², R³³, and R³⁴ include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, t-butyl, amyl, isoamyl, t-amyl, hexyl, heptyl, octyl, isooctyl, 2-ethylhexyl, t-octyl, nonyl, isononyl, decyl, isodecyl, undecyl, dodecyl, cyclopentyl, cyclohexyl, vinyl, allyl, butenyl, ethynyl, propynyl, methoxyethyl, ethoxyethyl, propoxyethyl, pentyloxyethyl, octyloxyethyl, methoxyethoxyethyl, ethoxyethoxyethyl, propoxyethoxyethyl, methoxypropyl, and 2-(benzoxazol-2′-yl)ethenyl. Preferred of them are those having 3 to 8 carbon atoms. Examples of the aryl group as represented R¹¹, R¹², R¹³, R²¹, R²², R²³, R³¹, R³²R³³, and R³⁴ include phenyl, tolyl, xylyl, ethylphenyl, chlorophenyl, naphthyl, anthryl, and phenanthryl. Preferred of them are those having 6 to 12 carbon atoms. Examples of the arylalkyl group as represented by R¹¹, R¹², R¹³, R²¹, R²², R²³, R³¹, R³², R³³, and R³⁴ include those having 7 to 13 carbon atoms, such as benzyl, chlorobenzoyl, α-methylbenzyl, α,α-dimethylbenzyl, phenylethyl, and phenylethenyl. The heterocyclic group as represented by R¹¹, R¹², R¹³, R²¹, R²², R²³, R³¹, R³², R³³, and R³⁴ is preferably a 5- to 7-membered heterocyclic group, including pyridyl, pyrimidyl, furyl, thienyl, tetrahydrofuryl, and dioxolanyl. The ring formed by connecting R¹² and R¹³, the ring formed by connecting R²² and R²³, the ring formed by connecting R³ and R⁴, the cyclic structure formed by connecting R³ to one of the carbon atoms of the benzene rings neighboring via X, and the ring formed by connecting R³¹, R³³, or R³⁴ and a neighboring benzene ring are preferably 5- to 7-membered rings, such as cyclopentane, cyclohexane, cyclopentene, benzene, piperidine, morpholine, lactone, and lactam rings.

Examples of the halogen atom as a substituent of R¹¹, R¹², R¹³, R²¹, R²², R²³, R³¹, R³², R³³, and R³⁴ include fluorine, chlorine, bromine, and iodine. Examples of the heterocyclic group as a substituent of R¹¹, R¹², R¹³, R²¹, R²², R²³, R³¹, R³², R³³, and R³⁴ include 5- to 7-membered heterocyclic rings, such as pyridine, pyrimidyl, furyl, benzoxazol-2-yl, tetrahydropyranyl, pyrrolidyl, imidazolidyl, pyrazolidyl, thiazolidyl, isothiazolidyl, oxazolidyl, isooxazolidyl, piperidyl, piperazyl, and morpholinyl. Examples of the halogen atoms as represented by R³ and R⁴ include fluorine, chlorine, bromine, and iodine.

The methylene units of the alkylene moiety of the above described substituents may be interrupted by an unsaturated linkage, an ether linkage, a thioether linkage, an ester linkage, a thioester linkage, an amido linkage, or a urethane linkage at 1 to 5 sites. The interrupting linking groups may be the same or different. Two or more interrupting linking groups may be continued to each other, if possible. The alkyl moiety of the above described substituents may be branched or cyclic, and the alkyl terminal of the substituents may have an unsaturated bond.

Preferred of the oxime ester compounds of general formula (I) according to the invention are those in which R¹ is a halogen-substituted or unsubstituted aryl group having 6 to 30 carbon atoms, particularly a phenyl group; those in which R² is a cyclic or acyclic, halogen-substituted or unsubstituted alkyl group with 1 to 20 carbon atoms, particularly a methyl group; and those in which X is a sulfur atom or NR³³, and R³³ is a straight-chain, branched, or cyclic, halogen-substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, particularly an octyl group. These preferred compounds are easy to synthesize and show high sensitivity.

The oxime ester compound of the invention may be dimerized at R¹ to provide a compound represented by formulae shown below:

Examples of the preferred oxime ester compounds of general formula (I) include, but are not limited to, compound Nos. 1 through 24 below.

The process of synthesizing the oxime ester compound of general formula (I) according to the invention is not particularly limited. The compound in which X is a sulfur atom is prepared by, for example, the following process in accordance with the reaction scheme:

p-Chlororonitrobenzene 1 and thiophenol 2 are caused to react in the presence of sodium hydroxide to obtain a sulfide compound 3. The sulfide compound 3 is allowed to react with an acid chloride 4 in the presence of aluminum chloride to obtain an acylated compound 5, which is then allowed to react with an alkyl nitrite 6 and then with an acid anhydride 7 or an acid chloride 7′ to yield the oxime ester compound of general formula (I) wherein X is sulfur. Oxime ester compounds in which X is oxygen, selenium, CR³³R34, N—R³³, or P—R³⁴ are prepared in accordance with the above-described process.

The oxime ester compound of the invention is useful as an initiator for photopolymerization of a polymerizable compound having an ethylenically unsaturated bond.

The photosensitive composition according to the invention will then be described. The photosensitive composition of the invention contains a photopolymerization initiator having the oxime ester compound as an active ingredient, an ethylenically unsaturated polymerizable compound, and, if desired, an inorganic compound and/or a colorant, and other optional components such as a solvent.

Any ethylenically unsaturated polymerizable compound that has been used in a photosensitive composition can be used in the invention. Examples include unsaturated aliphatic hydrocarbons, such as ethylene, propylene, butylene, isobutylene, vinyl chloride, vinylidene chloride, vinylidene fluoride, and tetrafluoroethylene; a polymer having a carboxyl group and a hydroxyl group at both terminals, such as (meth)acrylic acid, α-chloroacrylic acid; itaconic acid, maleic acid, citraconic acid, fumaric acid, hymic acid, crotonic acid, isocrotonic acid, vinylacetic acid, allylacetic acid, cinnamic acid, sorbic acid, mesaconic acid, trimellitic acid, pyromellitic acid, 2,2′,3,3′-benzophenonetetracarboxylic acid, 3,3,4,4′-benzophenonetetracarboxylic acid, mono[2-(meth)acryloyloxyethyl]succinate, mono[2-(meth)acryloyloxyethyl]phthalate, a mono(methacrylate) and co-carboxypolycaprolactone mono(meth)acrylate; unsaturated polybasic acids such as hydroxyethyl(meth)acrylate malate, hydroxypropyl(meth)acrylate malate, dicyclopentadiene malate, and a polyfunctional (meth)acrylate having one carboxyl group and two or more (meth)acryloyl groups; esters between an unsaturated monobasic acid and a polyhydric alcohol or a polyhydric phenol, such as 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, glycidyl(meth)acrylate, compound Nos. 25 to 28 shown below, methyl(meth)acrylate, butyl(meth)acrylate, isobutyl(meth)acrylate, t-butyl(meth)acrylate, cyclohexyl(meth)acrylate, n-octyl(meth)acrylate, isooctyl(meth)acrylate, isononyl(meth)acrylate, stearyl(meth)acrylate, lauryl(meth)acrylate, methoxyethyl(meth)acrylate, dimethylaminomethyl(meth)acrylate, dimethylaminoethyl(meth)acrylate, aminopropyl(meth)acrylate, dimethylaminopropyl(meth)acrylate, ethoxyethyl(meth)acrylate, poly(ethoxy)ethyl(meth)acrylate, butoxyethoxyethyl(meth)acrylate, ethylhexyl(meth)acrylate, phenoxyethyl(meth)acrylate, tetrahydrofuryl(meth)acrylate, vinyl(meth)acrylate, allyl(meth)acrylate, benzyl(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolethane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol penta(meth)acrylate, pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, tricyclodecanedimethylol di(meth)acrylate, tri[(meth)acryloylethyl] isocyanurate, and polyester(meth)acrylate oligomers; metal salts of unsaturated polybasic acids, such as zinc(meth)acrylate and magnesium(meth)acrylate; unsaturated polybasic acid anhydrides, such as maleic anhydride, itaconic anhydride, citraconic anhydride, methyltetrahydrophthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydrides, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, trialkyltetrahydrophthalic anhydride-maleic anhydride adducts, dodecenylsuccinic anhydride, and methylhymic anhydride; amides formed between an unsaturated monobasic acid and a polyfunctional amine, such as (meth)acrylamide, methylenebis(meth)acrylamide, diethyl enetriaminetris(meth)acrylamide, xylylenebis(meth)acrylamide, α-chloroacrylamide, and N-2-hydroxyethyl(meth)acrylamide; unsaturated aldehydes, such as acrolein; unsaturated nitriles, such as (meth)acrylonitrile, α-chloroacrylonitrile, vinylidene cyanide, and allyl cyanide; unsaturated aromatic compounds, such as styrene, 4-methylstyrene, 4-ethylstyrene, 4-methoxystyrene, 4-hydroxystyrene, 4-chlorostyrene, divinylbenzene, vinyltoluene, vinylbenzoic acid, vinylphenol, vinylsulfonic acid, 4-vinylbenzenesulfonic acid, vinylbenzyl methyl ether, and vinylbenzyl glycidyl ether; unsaturated ketones, such as methyl vinyl ketone; unsaturated amine compounds, such as vinylamine, allylamine, N-vinylpyrrolidone, and vinylpiperidine; vinyl alcohols, such as allyl alcohol and crotyl alcohol; vinyl ethers, such as vinyl methyl ether, vinyl ethyl ether, n-butyl vinyl ether, isobutyl vinyl ether, and allyl glycidyl ether; unsaturated imides, such as maleimide, N-phenylmaleimide, and N-cyclohexylmaleimide; indenes, such as indene and 1-methylindene; aliphatic conjugated dienes, such as 1,3-butadiene, isoprene, and chloroprene; macromonomers having a mono(meth)acryloyl group at the terminal of a polymeric molecular chain, such as polystyrene, polymethyl(meth)acrylate, poly-n-butyl(meth)acrylate, and polysiloxanes; vinyl chloride, vinylidene chloride, divinyl succinate, diallyl phthalate, triallyl phosphate, triallyl isocyanurate, vinyl thioether, vinylimidazole, vinyloxazoline, vinylcarbazole, vinylpyrrolidone, vinylpyridine, vinylurethane compounds formed between a hydroxyl-containing vinyl monomer and a polyisocyanate compound, and vinylepoxy compounds formed between a hydroxyl-containing vinyl monomer and a polyepoxy compound. Of these ethylenically unsaturated polymerizable compounds, a (mono)methacrylate of a polymer having a carboxyl group and a hydroxyl group at both terminals, a polyfunctional (meth)acrylate having one carboxyl group and two or more (meth)acryloyl groups, and an ester between an unsaturated monobasic acid and a polyhydric alcohol or polyhydric phenol are suited to be polymerized by using the photopolymerization initiator containing the oxime ester compound of the invention as an active ingredient.

The polymerizable compounds may be used either individually or as a mixture of two or more thereof. The two or more polymerizable compounds to be used in combination may be in the form of a copolymer previously prepared therefrom.

When the ethylenically unsaturated polymerizable compound is an ethylenically unsaturated, alkali-developable compound, the photosensitive composition of the invention serves as an alkali-developable photosensitive resin composition. Examples of the ethylenically unsaturated, alkali-developable compound include acrylic ester copolymers, phenol and/or cresol novolak epoxy resins, polyphenylmethane epoxy resins having two or more epoxy groups, and resins obtained by causing an epoxy compound, such as a compound represented by general formula (II) below, and an unsaturated monobasic acid to react with each other and causing the resulting reaction product to react with a polybasic acid anhydride. Preferred of them are resins obtained by causing an epoxy compound, such as a compound represented by general formula (II) below, and an unsaturated monobasic acid to react with each other and causing the resulting product to react with a polybasic acid anhydride. The ethylenically unsaturated, alkali-developable compound preferably contains 0.2 to 1.0 equivalents of an unsaturated group.

wherein X¹ represents a single bond, a methylene group, a halogen-substituted or unsubstituted alkylidene group having 1 to 4 carbon atoms, an alicyclic hydrocarbon group having 3 to 20 carbon atoms, O, S, SO₂, SS, SO, CO, OCO, or a substituent represented by formula A or B below; R⁴¹, R⁴², R⁴³, and R⁴⁴ each independently represent a hydrogen atom, a halogen-substituted or unsubstituted alkyl group having 1 to 5 carbon atoms, a halogen-substituted or unsubstituted alkoxy group having 1 to 8 carbon atoms, a halogen-substituted or unsubstituted alkenyl group having 2 to 5 carbon atoms, or a halogen atom; and m represents an integer of 0 to 10.

wherein Y¹ represents a hydrogen atom, a phenyl group which may be substituted with an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, or a cycloalkyl group having 3 to 10 carbon atoms; Z¹ represents a halogen-substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a halogen-substituted or unsubstituted alkoxy group having 1 to 10 carbon atoms, a halogen-substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, or a halogen atom; and d represents an integer of 0 to 5.

Examples of the unsaturated monobasic acid which is caused to react on the epoxy compound include acrylic acid, methacrylic acid, crotonic acid, cinnamic acid, sorbic acid, hydroxyethyl methacrylate malate, hydroxyethyl acrylate malate, hydroxypropyl methacrylate malate, hydroxypropyl acrylate malate, and dicyclopentadiene malate.

Examples of the polybasic acid anhydride that is caused to react after the reaction of the unsaturated monobasic acid include biphenyltetracarboxylic acid dianhydride, tetrahydrophthalic anhydride, succinic anhydride, biphthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, 2,2′,3,3′-benzophenonetetracarboxylic acid anhydride, ethylene glycol bisanhydrotrimellitate, glycerol trisanhydrotrimellitate, hexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, nadic anhydride, methylnadic anhydride, trialkyltetrahydrophthalic anhydrides, hexahydrophthalic anhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, trialkyltetrahydrophthalic anhydride-maleic anhydride adducts, dodecenylsuccinic anhydride, and methylhymic anhydride.

The epoxy compound and the unsaturated monobasic acid are preferably used in such a molar ratio that results in the formation of an epoxy adduct having 0.1 to 1.0 carboxyl group of the unsaturated monobasic acid added per epoxy group of the epoxy compound. The polybasic acid anhydride is preferably used in such a molar ratio as to provide 0.1 to 1.0 acid anhydride structure per hydroxyl group of the resulting epoxy adduct.

The reactions of the epoxy compound, unsaturated monobasic acid, and polybasic acid anhydride are carried out in a usual manner.

In order to improve developability of the alkali-developable photosensitive resin composition, either colored or not colored, the acid value of the ethylenically unsaturated alkali-developable compound may be adjusted by using a mono- or polyfunctional epoxy compound in combination with the ethylenically unsaturated, alkali-developable compound. It is preferred that the solid content of the ethylenically unsaturated, alkali-developable compound to have an acid value of 5 to 120 mg-KOH/g. The amount of the mono- or polyfunctional epoxy compound to be used is preferably chosen so as to satisfy the above recited range of acid value.

Examples of the monofunctional epoxy compound include glycidyl methacrylate, methyl glycidyl ether, ethyl glycidyl ether, propyl glycidyl ether, isopropyl glycidyl ether, butyl glycidyl ether, isobutyl glycidyl ether, t-butyl glycidyl ether, pentyl glycidyl ether, hexyl glycidyl ether, heptyl glycidyl ether, octyl glycidyl ether, nonyl glycidyl ether, decyl glycidyl ether, undecyl glycidyl ether, dodecyl glycidyl ether, tridecyl glycidyl ether, tetradecyl glycidyl ether, pentadecyl glycidyl ether, hexadecyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, propargyl glycidyl ether, p-methoxyethyl glycidyl ether, phenyl glycidyl ether, p-methoxyglycidyl ether, p-butylphenyl glycidyl ether, cresyl glycidyl ether, 2-methylcresyl glycidyl ether, 4-nonylphenyl glycidyl ether, benzyl glycidyl ether, p-cumylphenyl glycidyl ether, trimethyl glycidyl ether, 2,3-epoxypropyl methacrylate, epoxidized soybean oil, epoxidized linseed oil, glycidyl butyrate, vinylcyclohexene monoxide, 1,2-epoxy-4-vinylcyclohexane, styrene oxide, pinene oxide, methylstyrene oxide, cyclohexene oxide, propylene oxide, and compound Nos. 29 and 30 below.

The polyfunctional epoxy compound is preferably at least one compound selected from the group consisting of bisphenol epoxy compounds and glycidyl ethers. Using at least one of them is effective in providing a (colored) alkali developable photosensitive resin composition having further improved characteristics. Examples of the bisphenol epoxy compounds include the epoxy compounds represented by general formula (II) and others including hydrogenated bisphenol epoxy compounds. Examples of the glycidyl ethers include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, 1,8-octanediol diglycidyl ether, 1,10-decanediol diglycidyl ether, 2,2-dimethyl-1,3-propanediol diglycidyl ether, diethylene glycol diglycidyl ether, triethylene glycol diglycidyl ether, tetraethylene glycol diglycidyl ether, hexaethylene glycol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, 1,1,1-tri(glycidyloxymethyl)propane, 1,1,1-tri(glycidyloxymethyl)ethane, 1,1,1-tri(glycidyloxymethyl)methane, and 1,1,1,1-tetra(glycidyloxymethyl)methane.

Other useful polyfunctional epoxy compounds include novolak epoxy compounds, such as phenol novolak epoxy compounds, biphenyl novolak epoxy compounds, cresol novolak epoxy compounds, bisphenol A novolak epoxy compounds, and dicyclopentadiene novolak epoxy compounds; alicyclic epoxy compounds, such as 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, and 1-epoxyethyl-3,4-epoxycyclohexane; glycidyl esters, such as diglycidyl phthalate, diglycidyl tetrahydrophthalate, and glycidyl dimerate; glycidylamines, such as tetraglycidyl diaminodiphenylmethane, triglycidyl p-aminophenol, and N,N-diglycidylaniline; heterocyclic epoxy compounds, such as 1,3-diglycidyl-5,5-dimethylhydantoin and triglycidyl isocyanurate; dioxide compounds, such as dicyclopentadiene dioxide; naphthalene epoxy compounds, triphenylmethane epoxy compounds, and dicyclopentadiene epoxy compounds.

The amount of the photopolymerization initiator to be used in the photosensitive composition of the invention is preferably, but not limited to, 1 to 70 parts, more preferably 1 to 50 parts, even more preferably 5 to 30 parts, by mass per 100 parts by mass of the ethylenically unsaturated polymerizable compound.

In the case when the photosensitive composition is contemplated to be a (colored) alkali developable photosensitive resin composition, the content of the ethylenically unsaturated, alkali developable compound in the composition is preferably 1 to 20%, more preferably 3 to 12%, by mass.

The photosensitive composition of the invention may optionally contain a solvent. Usually, solvents capable of dissolving or dispersing the above described components (such as the oxime ester compound of the invention and the ethylenically unsaturated polymerizable compound) are used where necessary. Such solvents include ketones, e.g., methyl ethyl ketone, methyl amyl ketone, diethyl ketone, acetone, methyl isopropyl ketone, methyl isobutyl ketone, and cyclohexanone; ethers, such as ethyl ether, dioxane, tetrahydrofuran, 1,2-dimethoxyethane, 1,2-diethoxyethane, and dipropylene glycol dimethyl ether; esters, such as methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, and n-butyl acetate; cellosolve solvents, such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and propylene glycol monoethyl ether acetate; alcohols, such as methanol, ethanol, isopropyl alcohol, n-propanol, isobutanol, n-butanol, and amyl alcohol; ethers, such as ethylene glycol monomethyl acetate, ethylene glycol monoethyl acetate, and propylene glycol methyl acetate; BTX solvents (benzene, toluene, xylene, etc.); aliphatic hydrocarbons, such as hexane, heptane, octane, and cyclohexane; terpene hydrocarbon oils, such as turpentine oil, D-limonene, and pinene; paraffinic solvents, such as mineral spirit, Swazol #310 (available from Cosmo Matsuyama Oil Co., ltd.), and Solvesso #100 (available from Exxon Chemical); halogenated aliphatic hydrocarbons, such as carbon tetrachloride, chloroform, trichloroethylene, methylene chloride, and 1,2-dichloroethane; halogenated aromatic hydrocarbons, such as chlorobenzene; carbitol solvents, aniline, triethylamine, pyridine, acetic acid, acetonitrile, carbon disulfide, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, and water. These solvents may be used either individually or as a mixture of two or more thereof.

Preferred of them are cellosolve solvents, particularly propylene glycol-1-monomethyl ether-2-acetate, cyclohexanone, and so on in view of providing good compatibility between a resist and a photopolymerization initiator in a photosensitive composition.

The photosensitive composition may further contain an inorganic compound. Examples of the inorganic compound include metal oxides, such as nickel oxide, iron oxide, iridium oxide, titanium oxide, zinc oxide, magnesium oxide, calcium oxide, potassium oxide, silica, and alumina; layered clay minerals, Milori blue, calcium carbonate, magnesium carbonate, cobalt compounds, manganese compounds, glass powder, mica, talc, kaolin, ferrocyanides, various metal sulfates, sulfides, selenides, aluminum silicate, calcium silicate, aluminum hydroxide, platinum, gold, silver, and copper. Preferred of them are titanium oxide, silica, layered clay minerals, and silver. The inorganic compound content in the photosensitive composition is preferably 0.1 to 50 parts, more preferably 0.5 to 20 parts, by mass per 100 parts by mass of the ethylenically unsaturated polymerizable compound. The inorganic compounds may be used either individually or in combination of two or more thereof.

The inorganic compounds are used as, for example, a filler, an antireflection agent, an electrically conductive agent, a stabilizer, a flame retardant, a mechanical strength improving agent, a specific wavelength absorbing agent, an ink repellent agent, and the like.

The photosensitive composition of the invention, especially the alkali developable photosensitive resin composition may further contain a colorant to be formulated into a colored photosensitive composition. Pigments, dyes, and naturally occurring dyes are used as a colorant. The colorants may be used either individually or as a mixture of two or more thereof.

The pigments may be either organic or inorganic, including nitroso compounds, nitro compounds, azo compounds, diazo compounds, xanthene compounds, quinoline compounds, anthraquinone compounds, coumarin compounds, phthalocyanine compounds, isoindolinone compounds, isoindoline compounds, quinacridone compounds, anthanthrone compounds, perynone compounds, perylene compounds, diketopyrrolopyrrole compounds, thioindigo compounds, dioxazine compounds, triphenylmethane compounds, quinophthalone compounds, and naphthalenetetracarboxylic acids; metal complex compounds, such as azo dyes, and cyanine dyes; lake pigments; carbon black species, such as furnace black, channel black, thermal black, acetylene black, Ketjen black, and lamp black; the carbon blacks recited which have been surface treated with an acid or an alkali; graphite, graphitized carbon black, activated carbon, carbon fiber, carbon nanotube, carbon microcoil, carbon nanohom, carbon aerogel, fullerene; aniline black, pigment black 7, titanium black; hydrophobic resins, chromium oxide green, Milori blue, cobalt green, cobalt blue, manganese compounds, ferrocyanides, phosphate ultramarine blue, Prussian blue, ultramarine, cerulean blue, viridian, emerald green, lead sulfate, lead yellow, zinc yellow, Bengal red (red iron (III) oxide), cadmium red, synthetic iron black, and amber. The pigments may be used either individually or as a mixture thereof.

Commercially available pigments may be used, including pigment red 1, 2, 3, 9, 10, 14, 17, 22, 23, 31, 38, 41, 48, 49, 88, 90, 97, 112, 119, 122, 123, 144, 149, 166, 168, 169, 170, 171, 177, 179, 180, 184, 185, 192, 200, 202, 209, 215, 216, 217, 220, 223, 224, 226, 227, 228, 240, and 254; pigment orange 13, 31, 34, 36, 38, 43, 46, 48, 49, 51, 52, 55, 59, 60, 61, 62, 64, 65, and 71; pigment yellow 1, 3, 12, 13, 14, 16, 17, 20, 24, 55, 60, 73, 81, 83, 86, 93, 95, 97, 98, 100, 109, 110, 113, 114, 117, 120, 125, 126, 127, 129, 137, 138, 139, 147, 148, 150, 151, 152, 153, 154, 166, 168, 175, 180, and 185; pigment green 7, 10, and 36; pigment blue 15, 15:1, 15:2, 15:3, 15:4, 15:5, 15:6, 22, 24, 56, 60, 61, 62, and 64; and pigment violet 1, 19, 23, 27, 29, 30, 32, 37, 40, and 50.

Examples of the dyes include azo dyes, anthraquinone dyes, indigoid dyes, triarylmethane dyes, xanthene dyes, alizarine dyes, acridine dyes, stilbene dyes, thiazole dyes, naphthol dyes, quinoline dyes, nitro dyes, indamine dyes, oxazine dyes, phthalocyanine dyes, and cyanine dyes. The may be used as a mixture thereof.

The amount of the colorant to be added to the photosensitive composition is preferably 50 to 350 parts, more preferably 100 to 250 parts, by mass per 100 parts by mass of the ethylenically unsaturated polymerizable compound.

The photosensitive composition may further contain other organic polymer in addition to the ethylenically unsaturated polymerizable compound to provide a cured product with improved characteristics. Examples of the organic polymer include polystyrene, polymethyl methacrylate, methyl methacrylate-ethyl acrylate copolymers, poly(meth)acrylic acid, styrene-(meth)acrylic acid copolymers, (meth)acrylic acid-methyl methacrylate copolymers, ethylene-vinyl chloride copolymers, ethylene-vinyl copolymers, polyvinyl chloride resins, ABS resins, nylon 6, nylon 66, nylon 12, urethane resins, polycarbonate, polyvinyl butyral, cellulose esters, polyacrylamide, saturated polyesters, phenol resins, phenoxy resins, polyamide-imide resins, polyamic acid resins, and epoxy resins. Preferred of them are polystyrene, (meth)acrylic acid-methyl acrylate copolymers, and epoxy resins.

The amount of the other organic polymer is preferably 10 to 500 parts by mass per 100 parts by mass of the ethylenically unsaturated polymerizable compound.

The photosensitive composition may furthermore contain a monomer having an unsaturated bond, a chain transfer agent, a surfactant, and so on.

Examples of the monomer having an unsaturated bond include 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, isobutyl acrylate, n-octyl acrylate, isooctyl acrylate, isononyl acrylate, stearyl acrylate, methoxyethyl acrylate, dimethylaminoethyl acrylate, zinc acrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, butyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, trimethylolpropane trimethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, bisphenol A diglycidyl ether(meth)acrylate, bisphenol F diglycidyl ether(meth)acrylate, bisphenol Z diglycidyl ether(meth)acrylate, and tripropylene glycol di(meth)acrylate.

Examples of the chain transfer agent include mercapto compounds, such as thioglycolic acid, thiomalic acid, thiosalicylic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, 3-mercaptobutyric acid, N-(2-mercaptopropionyl)glycine, 2-mercaptonicotinic acid, 3-[N-(2-mercaptoethyl)carbamoyl]propionic acid, 3-[N-(2-mercaptoethyl)amino]propionic acid, N-(3-mercaptopropionyl)alanine, 2-mercaptoethanesulfonic acid, 3-mercaptopropanesulfonic acid, 4-mercaptobutanesulfonic acid, dodecyl (4-methylthio)phenyl ether, 2-mercaptoethanol, 3-mercapto-1,2-propanediol, 1-mercapto-2-propanol, 3-mercapto-2-butanol, mercaptophenol, 2-mercaptoethylamine, 2-mercaptoimidazole, 2-mercapto-3-pyridinol, 2-mercaptobenzothiazole, mercaptoacetic acid, trimethylolpropane tris(3-mercaptopropionate), and pentaerythritol tetrakis(3-mercaptopropionate); disulfide compounds obtained by oxidizing the recited mercapto compounds; and iodized alkyl compounds, such as iodoacetic acid, iodopropionic acid, 2-iodoethanol, 2-iodoethanesulfonic acid, and 3-iodopropanesulfonic acid.

Examples of the surfactant include fluorine-containing surfactants, such as perfluoroalkylphosphoric esters, perfluoroalkylcarboxylic acid salts; anionic surfactants, such as higher fatty acid alkali salts, alkylsulfonic acid salts, and alkylsulfuric acid salts; cationic surfactants, such as higher amine halogenic acid salts and quaternary ammonium salts; nonionic surfactants, such as polyethylene glycol alkyl ethers, polyethylene glycol fatty acid esters, sorbitan fatty acid esters, and fatty acid monoglycerides; amphoteric surfactants, and silicone surfactants. These surfactants may be used in combination thereof.

If desired, the photosensitive composition may contain other photopolymerization initiator or sensitizer in addition to the oxime ester compound of the invention. A combined use of other photopolymerization initiator can produce marked synergistic effects.

Any known photopolymerization initiators can be used in combination with the oxime ester compound. Examples of such initiators include benzophenone, phenyl biphenyl ketone, 1-hydroxy-1-benzoylcyclophexane, benzoin, benzyl dimethyl ketal, 1-benzyl-1-dimethylamino-1-(4′-morpholinobenzoyl)propane, 2-morpholyl-2-(4′-methylmercapto)benzoylpropane, thioxanthone, 1-chloro-4-propoxythioxanthone, isopropylthioxanthone, diethylthioxanthone, ethylanthraquinone, 4-benzoyl-4′-methyldiphenyl sulfide, benzoin butyl ether, 2-hydroxy-2-benzoylpropane, 2-hydroxy-2-(4′-isopropyl)benzoylpropane, 4-butylbenzoyltrichloromethane, 4-phenoxybenzoyldichloromethane, methyl benzoylformate, 1,7-bis(9′-acridinyl)heptane, 9-n-butyl-3,6-bis(2′-morpholinoisobutyroyl)carbazole, 2-methyl-4,6-bis(trichloromethyl)-s-triazine, 2-phenyl-4,6-bis(trichloromethyl)-s-triazine, 2-naphthyl-4,6-bis(trichloromethyl)-s-triazine, 2,2-bis(2-chlorophenyl)-4,5,4′,5% tetraphenyl-1,2′-biimidazole, 4,4-azobisisobutyronitrile, triphenylphosphine, camphorquinone; N-1414, N-1717, N-1919, and PZ-408 (from ADEKA Corp.); Irgacure 369, Irgacure 907, Irgacure OXE 01, and Irgacure OXE 02 (from Ciba Specialties Chemicals Corp.); benzoyl peroxide, and compounds represented by general formulae (III) to (V) shown below. These photopolymerization initiators can be used either individually or in a combination of two or more thereof. The amount of the known photopolymerization initiator(s), if used, is preferably equal to or less than the mass of the oxime ester compound of the invention.

wherein R¹ and R² are as defined for general formula (I); R⁶ has the same meaning as R¹; Y² represents a halogen atom or an alkyl group; and n represents 0 to 5.

wherein R¹ and R² are as defined for general formula (I); R⁶, Y² and n are as defined for general formula (III); R^(′1), R^(′2), and R^(′6) have the same meaning as R¹; Y^(′2) has the same meaning as Y²; R⁷ represents a diol residue or a dithiol residue; and Z² represents an oxygen atom or a sulfur atom.

wherein R¹ and R² are as defined for general formula (I); R⁶, Y², and n are as defined for general formula (III); Z³ represents an oxygen atom, a sulfur atom, or a selenium atom; A represents a heterocyclic group; p represents an integer of 0 to 5; and q is 0 or 1.

If desired, the photosensitive composition of the present invention may contain commonly used additives, including thermal polymerization inhibitors (e.g., p-anisole, hydroquinone, pyrocatechol, t-butylcatechol, and phenothiazine), plasticizers, adhesion accelerators, fillers, anti-foaming agents, leveling agents, surface modifiers, antioxidants, ultraviolet absorbers, dispersing acids, anti-coagulants, catalysts, effect accelerators, sensitizers, crosslinking agents, and thickeners.

The amounts of the optional components other than the ethylenically unsaturated polymerizable compound and the oxime ester compound, except the above described other photopolymerization initiator, inorganic filler, colorant, and solvent, in the photosensitive composition are decided as appropriate to the use of the composition. Preferably, the total amount of the optional components is not more than 50 parts by mass per 100 parts by mass of the ethylenically unsaturated polymerizable compound.

The photosensitive composition of the invention is applied to a substrate, such as soda glass, quartz glass, semiconductor substrates, metals, paper, or plastics. The method of application is not limited. Any known coating methods may be used, such as spin coating, roll coating, bar coating, die coating, curtain coating, printing, and dipping. The photosensitive composition may be once applied to a carrier substrate, such as a film, and then transferred to another substrate.

The photosensitive composition of the invention has unlimited application. It finds use in, for example, photocuring paints or varnishes, photocuring adhesives, printed boards; color filters for liquid crystal color display devices, such as TV monitors, PC monitors, personal digital assistances, and digital cameras; electrode materials for plasma display panels; powder coatings, printing inks, printing plates, adhesives, compositions for dental use, gel coats, photoresists for electronics, electroplating resists, etching resists, liquid and dry films, soldering resists; resists for producing color filters of various displays or for forming structures in the production of plasma display panels, electroluminescent displays, and LCDs; encapsulating compositions for electric/electronic components, magnetic recording materials, fine machine parts, waveguides, optical switches, plating masks, etching masks, color test systems, glass fiber cable coatings, screen printing stencils, materials for making a three-dimensional object by stereolithography, holographic recording materials, image recording materials, fine electronic circuits, decolorizing materials, decolorizing materials for image recording materials, decolorizing materials for image recording materials using microcapsules, photoresist materials for printed wiring boards, photoresist materials for direct image writing using UV and visible lasers, and photoresist materials or protective layers used to form dielectric layers in the fabrication of multilayered printed circuit boards.

The photosensitive composition containing the oxime ester compound of the invention can be cured with active light from light sources emitting light of wavelengths of from 300 to 450 nm. Such light sources include an ultrahigh pressure mercury lamps, mercury vapor arcs, carbon arcs, and xenon arcs.

EXAMPLES

The present invention will now be illustrated in greater detail with reference to Examples, but it should be understood that the invention is not deemed to be limited thereto.

Example 1 Preparation of Compound No. 1

Step 1—Preparation of Sulfide Compound

In a nitrogen atmosphere, 31.6 g (200 mmol) of p-chloronitrobenzene, 24.2 g (220 mmol) of thiophenol, and 139 g of dimethylacetamide were put in a reactor, and 25.0 g (300 mmol) of sodium hydroxide was added thereto, followed by stirring at 50° C. for 1 hour. After cooling to room temperature, the reaction mixture was subjected to oil-water separation using ethyl acetate/water. The solvent was removed by evaporation to give 46.2 g (99%) of yellow crystals (HPLC purity: 99%).

Step 2—Preparation of Acylated Compound

In a nitrogen atmosphere 64.0 g (480 mmol) of aluminum chloride and 186 g of dichloroethane were put in a reactor. To the reactor were slowly added dropwise 27.8 g (180 mmol) of phenylacetyl chloride, 34.7 g (150 mmol) of the sulfide compound obtained in step 1 above, and 186 g of dichloroethane in the order described under cooling with ice, followed by stirring at 5° C. for 30 minutes. The reaction mixture was poured into ice-water for oil-water separation. The solvent was removed, and the residue was recrystallized from a mixed solvent of chloroform and methanol to give 12.0 g (19%) of pale brown crystals (HPLC purity: 98%).

Step 3—Preparation of Compound No. 1

In a nitrogen atmosphere 11.5 g (33 mmol) of the acylated compound obtained in step 2 above and 6.24 g of dimethylformamide were put in a reactor. To the reactor was added dropwise 3.18 g (16.5 mmol) of sodium methoxide, and 3.13 g (36.3 mmol) of isoamyl nitrite was then added thereto dropwise at 10° C. on a water bath, followed by stirring at 10° to 20° C. for 1 hour. Butyl acetate and 5% hydrochloric acid were added to the reaction mixture for oil-water separation. The solvent was removed by evaporation, and 42.0 g of butyl acetate and then 3.71 g (36.3 mmol) of acetic anhydride were added to the residue, followed by stirring at 90° C. for 1 hour, followed by cooling to water. The reaction mixture was neutralized with a 5% aqueous solution of sodium hydroxide. After oil-water separation, the solvent was removed, and the residue was recrystallized from a mixed solvent of butyl acetate and dibutyl ether to yield 6.11 g (44%) of pale yellow crystals (HPLC purity: 99%), which were identified to be compound No. 1 as a result of various analyses. The results of analyses are shown below.

(1) Melting point: 92.3° C.

(2) ¹H-NMR spectrum (ppm)

2.21 (s, 3H), 7.43-7.51 (m, 7H), 7.59 (d, 1H), 7.60 (d, 1H), 8.12 (d, 2H), 8.17 (d, 2H)

(3) IR spectrum (cm⁻¹)

3433, 3060, 1779, 1676, 1586, 1518, 1475, 1446, 1405, 1340, 1276, 1215, 1179, 1080, 1012, 902, 850, 776, 742, 692, 663

(4) UV spectrum (in chloroform)

λ_(max)=346 nm

(5) Decomposition temperature (5% mass loss temperature at heating rate of 10° C./min in nitrogen atmosphere)

241.4° C.

Example 1B Preparation of Compound No. 15

Step 1—Preparation of Acylated Compound

In a nitrogen atmosphere 3.52 g (26.4 mmol) of aluminum chloride and 16 g of dichloroethane were put in a reactor, and 2.041 g (13.2 mmol) of phenylacetyl chloride, 3.893 g (12 mmol) of 3-nitro-N-octylcarbazole, and 16 g of dichloroethane were slowly added dropwise in the order described under cooling with ice. The mixture was stirred at 5° C. for 30 minutes and poured into ice-water for oil-water separation. The solvent was removed, and the residue was recrystallized from a mixed solvent of chloroform and methanol to give 3.889 g (73%) of yellow crystals (HPLC purity: 99%).

Step 2—Preparation of Compound No. 15

In a nitrogen atmosphere 3.762 g (8.5 mmol) of the acylated compound obtained in step 1 of Example 1B and 6.24 g of dimethylformamide were put in a reactor. To the reactor was added dropwise 0.820 g (4.25 mmol) of sodium methoxide, and 0.806 g (9.35 mmol) of isoamyl nitrite was then added thereto dropwise at 10° C. on a water bath, followed by stirring at 10° to 20° C. for 1 hour. Butyl acetate and 5% hydrochloric acid were added to the reaction mixture for oil-water separation. The solvent was removed by evaporation, and 13.0 g of butyl acetate and then 0.955 g (9.35 mmol) of acetic anhydride were added to the residue, followed by stirring at 90° C. for 1 hour, followed by cooling to water. The reaction mixture was neutralized with a 5% aqueous solution of sodium hydroxide. After oil-water separation, the solvent was removed, and the residue was recrystallized from a mixed solvent of butyl acetate and dibutyl ether to yield 1.725 g (40%) of colorless crystals (HPLC purity: 99%), which were identified to be compound No. 15 as a result of various analyses. The results of analyses are shown below.

(1) Melting point: 145.2° C.

(2) ¹H-NMR spectrum (ppm)

0.86 (t, 3H), 1.18-1.43 (m, 10H), 1.91 (tt, 2H), 2.01 (s, 3H), 4.39 (t, 2H), 7.43 (ddd, 2H), 7.50 (d, 1H), 7.51 (dddd, 1H), 7.56 (d, 1H), 7.82 (ddd, 2H), 8.19 (dd, 1H), 8.45 (dd, 1H), 8.73 (s, 1H), 9.04 (s, 1H)

(3) IR spectrum (cm⁻¹)

3436, 2927, 1787, 1669, 1628, 1596, 1520, 1482, 1334, 1234, 1179, 1146, 1128, 1092, 912, 889, 826, 759, 727, 696, 658

(4) UV spectrum (in chloroform)

λ_(max)=364 nm

(5) Decomposition temperature (5% mass loss temperature at heating rate of 10° C./min in nitrogen atmosphere)

269.2° C.

Example 2 Preparation of Photosensitive Composition No. 1

To 14.0 g of an acrylic copolymer were added 5.90 g of trimethylolpropane triacrylate, 2.70 g of compound No. 1 obtained in Example 1, and 79.0 g of ethyl cellosolve, and the mixture was thoroughly stirred to obtain photosensitive composition No. 1.

The acrylic copolymer used above was obtained by dissolving 20 parts by mass of methacrylic acid, 15 parts by mass of hydroxyethyl methacrylate, 10 parts by mass of methyl methacrylate, and 55 parts by mass of butyl methacrylate in 300 parts by mass of ethyl cellosolve, adding thereto 0.75 parts by mass of azobisisobutyronitrile, followed by heating at 70° C. for 5 hours in a nitrogen atmosphere.

Example 3 Preparation of Photosensitive Composition No. 2

Dipentaerythritol pentaacrylate (15.0 g) and 3.74 g of 1,4-butanediol diglycidyl ether were mixed, and 3.30 g of compound No. 1 obtained in Example 1 and 78 g of ethyl cellosolve were added thereto, followed by thoroughly stirring to make photosensitive composition No. 2.

Example 4 Preparation of Photosensitive Composition No. 3 as Alkali-Developable Photosensitive Resin Composition

Step 1—Preparation of Alkali Developable Resin Composition No. 3

In a reactor were put 17.0 g of 1,1-bis(4′-epoxypropyloxyphenyl)-1-(1″-biphenyl)-1-cyclohexylmethane, 4.43 g of acrylic acid, 0.06 g of 2,6-di-tert-butyl-p-cresol, 0.11 g of tetrabutylammonium acetate, and 14.3 g of propylene glycol-1-monomethyl ether-2-acetate and stirred at 120° C. for 16 hours. The reaction system was cooled room temperature, and 7.18 g of propylene glycol-1-monomethyl ether-2-acetate, 4.82 g of succinic anhydride, and 0.25 g of tetrabutylammonium acetate, were added thereto, followed by stirring at 100° C. for 5 hours. To the mixture were further added 5.08 g of 1,1-bis(4′-epoxypropyloxyphenyl)-1-(1″-biphenyl)-1-cyclohexylmethane and 2.18 g of propylene glycol-1-monomethyl ether-2-acetate, and the mixture was stirred at 120° C. for 12 hours, 80° C. for 2 hours, and 40° C. for 2 hours. Finally, 13.1 g of propylene glycol-1-monomethyl ether-2-acetate was added to give alkali developable resin composition No. 3 in the form of a propylene glycol-1-monomethyl ether-2-acetate solution (Mw=4200; Mn=2100; acid value (solid basis): 55 mg-KOH/g).

Step 2—Preparation of Photosensitive Composition No. 3

Alkali developable resin composition No. 3 obtained in step 1 of Example 4 (2.68 g), 0.73 g of trimethylolpropane triacrylate, 7.91 g of propylene glycol-1-monomethyl ether-2-acetate, and 5.18 g of cyclohexanone were mixed. Compound No. 1 obtained in Example 1 (1.58 g) was added thereto, followed by stirring well to give photosensitive composition No. 3 as an alkali developable photosensitive resin composition.

Example 5 Preparation of Photosensitive Composition No. 4 as Alkali-Developable Photosensitive Resin Composition

Step 1—Preparation of Alkali Developable Resin Composition No. 4

In a reactor were put 184 g of a bisphenol fluorene epoxy resin (epoxy equivalent: 231), 58.0 g of acrylic acid, 0.26 g of 2,6-di-tert-butyl-p-cresol, 0.11 g of tetrabutylammonium acetate, and 23.0 g of propylene glycol-1-monomethyl ether-2-acetate and stirred at 120° C. for 16 hours. After cooling to room temperature, 35.0 g of propylene glycol-1-monomethyl ether-2-acetate, 59.0 g of biphthalic anhydride, and 0.24 g of tetra-n-butylammonium bromide were added to the reaction system, followed by stirring at 120° C. for 4 hours. To the mixture were further added 20 g of tetrahydrophthalic anhydride, and the mixture was stirred at 120° C. for 4 hours, 100° C. for 3 hours, 80° C. for 4 hours, 60° C. for 6 hours, and 40° C. for 11 hours. Finally, 90.0 g of propylene glycol-1-monomethyl ether-2-acetate was added to give alkali developable resin composition No. 4 in the form of a propylene glycol-1-monomethyl ether-2-acetate solution (Mw=5000; Mn=2100; acid value (solid basis): 92.7 mg-KOH/g).

Step 2—Preparation of Photosensitive Composition No. 4

Alkali developable resin composition No. 4 obtained in step 1 of Example 5 (2.68 g), 0.73 g of trimethylolpropane triacrylate, 7.91 g of propylene glycol-1-monomethyl ether-2-acetate, and 5.18 g of cyclohexanone were mixed. Compound No. 1 obtained in Example 1 (1.58 g) was added thereto to give photosensitive composition No. 4 as an alkali developable photosensitive resin composition.

Example 6 Preparation of Photosensitive Composition No. 5 as Colored Alkali-Developable Photosensitive Resin Composition

Photosensitive composition No. 5, which was a colored alkali-developable photosensitive resin composition, was prepared in the same manner as in Example 4, except for further adding 2.00 g of pigment blue 15.

Example 7 Preparation of Photosensitive Composition No. 6 as Colored Alkali-Developable Photosensitive Resin Composition

Photosensitive composition No. 6, which was a colored alkali-developable photosensitive resin composition, was prepared in the same manner as in Example 5, except for further adding 3.00 g of carbon black.

Example 8 Preparation of Photosensitive Composition No. 9

Photosensitive composition No. 9 was prepared in the same manner as in Example 2, except for further adding 4.52 g of titanium oxide.

Comparative Example 1 Preparation of Photosensitive Composition No. 7

Photosensitive resin composition No. 7 for comparison was prepared in the same manner as in Example 3, except for replacing compound No. 1 obtained in Example 1 with 3.30 g of comparative compound 1 shown below.

Comparative Example 2 Preparation of Photosensitive Composition No. 8 as Alkali Developable Photosensitive Resin Composition

Photosensitive resin composition No. 8 as a comparative alkali developable photosensitive resin composition was prepared in the same manner as in Example 4, except for replacing 1.58 g of compound No. 1 obtained in Example 1 with 1.58 g of comparative compound 1.

Photosensitive composition No. 2 and photosensitive composition No. 7 for comparison were tested for hardness as follows. The results obtained are shown in Table 1.

Photosensitive composition No. 3, which was an alkali developable photosensitive resin composition, and photosensitive resin composition No. 8, which was a comparative alkali developable photosensitive resin composition, were evaluated for sensitivity as follows. The results are shown in Table 2.

Hardness Test

The photosensitive composition was applied to a 50 μm thick polyethylene terephthalate film with a #3 bar coater and irradiated with light of a high pressure mercury lamp (80 W/cm) using a light irradiator equipped with a belt conveyor. The distance between the lamp and the belt conveyor was 10 cm. The linear speed of the belt conveyor was 8 cm/min. After the thus cured coating layer was left to stand at room temperature for 24 hours, the hardness was measured using a pencil hardness tester under a load of 1 kg.

Sensitivity

The alkali developable photosensitive resin composition was applied to an aluminum plate with a #3 bar coater to a thickness of about 1 μm, prebaked at 60° C. for 15 minutes, and exposed to light of an ultra-high pressure mercury lamp using a spectrophotometer CT-25CP form JASCO Corp. The exposed coating layer was dipped in a 2.5 mass % solution of sodium carbonate at 25° C., followed by thoroughly washing with water. The spectral sensitivity at 365 nm and 405 nm was evaluated in terms of the minimum energy of light at 365 nm and 405 nm necessary for the coating layer to sufficiently cure to remain on the aluminum plate.

TABLE 1 Photosensitive Composition Pencil Hardness No. 2 (Example 3) 3H No. 7 (Comparative Example 1) 1H

TABLE 2 Photosensitive Sensitivity (mJ/cm²) Composition 365 nm 405 nm No. 3 (Example 4) 3.3 2.4 No. 8 (Comp. Example 2) 18.6 76.2

Photosensitive composition No. 2 of Example 3 gained high hardness on curing, whereas photosensitive composition No. 7 of Comparative Example 1 failed to provide sufficient hardness. Alkali developable photosensitive resin composition No. 3 of Example 4 exhibited high sensitivity to light of long wavelengths, i.e., 365 nm and 405 nm, whereas alkali developable photosensitive resin composition No. 8 of Comparative Example 2 required an increased amount of energy for exposure at 365 nm and 405 nm on account of low sensitivity to these wavelengths of light.

INDUSTRIAL APPLICABILITY

The oxime ester compound of the invention exhibits high photosensitivity, particularly to long wavelengths of light at 365 nm (i-rays) and 405 nm (h-rays), and is therefore useful as a photopolymerization initiator. 

The invention claimed is:
 1. An oxime ester compound represented by general formula (I):

wherein: R¹ is a halogen-substituted or unsubstituted aryl group having 6 to 30 carbon atoms; R² is a cyclic or acyclic, halogen-substituted or unsubstituted alkyl group having 1 to 20 carbon atoms; R³ and R⁴ each independently represent R¹¹, OR¹¹, CN, a halogen atom, or a hydroxyl group; R¹¹ represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms; a and b each independently represent 0 to 4; X represents a sulfur atom or NR³³; R³³ is a straight-chain, branched, or cyclic, halogen-substituted or unsubstituted alkyl group having 1 to 20 carbon atoms; and R³ may be connected to one of the carbon atoms of the benzene rings neighboring via —X— to form a cyclic structure; or R³ and R⁴ may be connected to each other to form a ring.
 2. A photopolymerization initiator comprising the oxime ester compound according to claim 1 as an active ingredient.
 3. A photosensitive composition comprising the photopolymerization initiator according to claim 2 and a polymerizable compound having an ethylenically unsaturated bond.
 4. The photosensitive composition according to claim 3, further comprising an inorganic compound.
 5. An alkali-developable photosensitive resin composition comprising the photopolymerization initiator according to claim 2 and an alkali-developable compound having an ethylenically unsaturated compound.
 6. A colored alkali-developable photosensitive resin composition comprising the alkali-developable photosensitive resin composition according to claim 5 and a colorant. 